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  <div id="layout-content"><div id="function.bcsqrt" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">bcsqrt</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">bcsqrt</span> &mdash; <span class="dc-title">任意精度数字的二次方根</span></p>

 </div>
 
 <div class="refsect1 description" id="refsect1-function.bcsqrt-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>bcsqrt</strong></span>(<span class="methodparam"><span class="type">string</span> <code class="parameter">$num</code></span>, <span class="methodparam"><span class="type">?</span><span class="type"><span class="type">int</span><span class="type"></span></span> <code class="parameter">$scale</code><span class="initializer"> = <strong><code>null</code></strong></span></span>): <span class="type">string</span></div>

  <p class="para rdfs-comment">
   返回 <code class="parameter">num</code> 的二次方根。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.bcsqrt-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">num</code></dt>

     <dd>

      <p class="para">
       字符串类型的操作数。
      </p>
     </dd>

    
    <dt>

<code class="parameter">scale</code></dt>
<dd>
<p class="para">此可选参数用于设置结果中小数点后的小数位数。也可通过使用
<span class="function"><a href="function.bcscale.html" class="function">bcscale()</a></span> 来设置全局默认的小数位数，用于所有函数。如果未设置，则默认为 <code class="literal">0</code>。
</p></dd>

   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.bcsqrt-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   以 string 类型返回二次方根的结果，如果 <code class="parameter">num</code> 是负数则返回 <strong><code>null</code></strong>。
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.bcsqrt-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
      <td>8.0.0</td>
      <td>
       现在 <code class="parameter">scale</code> 可以为 null。
      </td>
     </tr>

    </tbody>
   
  </table>

 </div>

 
 <div class="refsect1 examples" id="refsect1-function.bcsqrt-examples">
  <h3 class="title">范例</h3>
  <div class="example" id="example-3031">
   <p><strong>示例 #1 <span class="function"><strong>bcsqrt()</strong></span> 示例</strong></p>
   <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">echo&nbsp;</span><span style="color: #0000BB">bcsqrt</span><span style="color: #007700">(</span><span style="color: #DD0000">'2'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">3</span><span style="color: #007700">);&nbsp;</span><span style="color: #FF8000">//&nbsp;1.414<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
   </div>

  </div>
 </div>

 
 <div class="refsect1 seealso" id="refsect1-function.bcsqrt-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.bcpow.html" class="function" rel="rdfs-seeAlso">bcpow()</a> - 任意精度数字的乘方</span></li>
   </ul>
  </p>
 </div>

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